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Author Topic: Stuttering/Surging when cold  (Read 596 times)

Graylic

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Stuttering/Surging when cold
« on: April 24, 2014, 03:45:25 AM »
Beginning last fall my g5 has been stuttering and loosing power when cold(outside temp <50F) most noticeable when getting on the highway about 1 mile into my morning commute.  I do not typically have any issues on the hilly 30mph street leading up to the highway, but when I try to accelerate up to 50 from a stop the bike will go between full power and hardly anything.  Once finally up to speed the problem mostly goes away, and there is no issue once the bike is warmed up.  Another possibly related issue is that I intermittently have difficulty kick starting the bike(I know how to find tdc), and the bike will sometimes not idle when cold with out a bit of throttle.  E-start is fine as long as I give the throttle a slight twist.
I initially assumed this was related to my terminally leaky exhaust header gasket but that has been fixed.
The bike has 3300 miles on it, runs great otherwise, and the spark plug has been replaced.
Possible causes to look into:
paint in the fuel filter
loose electrical connections/low battery
EFI not properly mapped for cold weather
Any other ideas?
1990 Suzuki DR250
2013 Royal Enfield G5

High On Octane

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Re: Stuttering/Surging when cold
« Reply #1 on: April 24, 2014, 11:37:26 AM »
How long are you letting the bike run before you jump on and ride?  I have a feeling that you're not letting the bike warm up enough before riding, especially when the temp is below 50*.  In that kind of weather (or even nice weather for that matter) you need to make sure the bike warms up for at least 5 minutes or so before the bike even comes out of open loop.  It sounds to me like the bike is still cold and in open loop and running lean when you are trying to accelerate hard onto the highway.

Scottie J
Scottie J
Denver, CO

1958 Enfield/Indian Trailblazer

Graylic

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Re: Stuttering/Surging when cold
« Reply #2 on: April 24, 2014, 01:50:15 PM »
I was wondering if that might be the issue as I am often in a bit of a rush on my way to work in the morning.  I'll check and see if a good warm up solves it. 
1990 Suzuki DR250
2013 Royal Enfield G5

TomJohnston

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Re: Stuttering/Surging when cold
« Reply #3 on: April 24, 2014, 01:54:13 PM »
Educate me please.......what do you mean by "coming out of open loop" ? I often ride my (2014 C5) in very cold mornings...like 25 to 35 degrees F.

Markku

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Re: Stuttering/Surging when cold
« Reply #4 on: April 24, 2014, 02:19:54 PM »
Same symptoms.  New battery and everything is OK. Hope it works also for you.  Greetings From Finland.
Markku

ace.cafe

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Re: Stuttering/Surging when cold
« Reply #5 on: April 24, 2014, 02:28:06 PM »
Educate me please.......what do you mean by "coming out of open loop" ? I often ride my (2014 C5) in very cold mornings...like 25 to 35 degrees F.

The bike starts on open loop, meaning that the O2 sensor isn't up to operating temperature yet, and so the computer can't get the feedback from the O2 sensor to adjust mixture. Once the O2 sensor heats up, then the computer can get the feedback and make the mixture adjustments accordingly. Then it operates in closed loop.
There is a heater in the O2 sensor which helps to get it up to temp faster, but it cuts out after about 2 minutes.

Probably some more warm up time would be appropriate.
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suitcasejefferson

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Re: Stuttering/Surging when cold
« Reply #6 on: April 24, 2014, 05:55:08 PM »
I wouldn't even consider riding a bike, or driving a car until it has warmed up, which will take several minutes even in fairly warm weather. Metal is much weaker when cold (also when too hot) and putting a load on it can cause it to warm up too fast, causing damage from thermal shock. Cold metal also just plain wears faster. Ask any pilot.

As for the stuttering/surging, The EFI on the Enfield is not the same as what you find on Japanese bikes. They start right up and run perfectly immediately. My Bullet takes about 5 minutes of idling before it really runs right. And it is not cold here. The RE EFI even has an enrichener lever on it for cold starts, which no Japanese EFI bike has.
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gashousegorilla

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Re: Stuttering/Surging when cold
« Reply #7 on: April 24, 2014, 06:45:42 PM »
 o2 sensor AFTER the temp sensor See's the right temp, at  the head in the oil passage...... GOOOD oil pump! And it's "Rich" prior to that, or at least a lot of fuel... whats burning, the "Mix" may still be lean, until it warms up ! Liquid fuel don't burn !   It wants the bike up to operating temp to make corrections.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Markku

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Re: Stuttering/Surging when cold
« Reply #8 on: April 25, 2014, 08:07:43 AM »
Hello again.  Drew this morning with the new battery and temperature was 40 F.  After about one mile b5 began stuttering for about one mile and then driving was OK.  With the weak battery the symptoms were the same but began earlier. Propably stuttering will begin,  when the motor oil temperature reaches 80 C (176 F) and the system goes to closed loop operation.
There is no air temperature sensor in the system and in cold weather oxygen content is higher and fuel leaner in situation
when system goes to closed loop and that might be the reason for stuttering before the system finds the correct mixture.
Markku

Graylic

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Re: Stuttering/Surging when cold
« Reply #9 on: April 26, 2014, 03:46:12 AM »
Well, I let the bike warm up a bit yesterday and today, and did not have any issues.  Unfortunately, both mornings I was stuck behind rather lethargic vehicles when I got on the highway, so I may have just not accelerated hard enough to instigate the symptoms.  Insufficient warmup does sound like the most likely culprit though.
1990 Suzuki DR250
2013 Royal Enfield G5

Roeland

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Re: Stuttering/Surging when cold
« Reply #10 on: April 26, 2014, 05:02:12 PM »
After I start the bike I usually have a smoke before I kick off... that's about 5 to 7 minutes.

whoguy

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Re: Stuttering/Surging when cold
« Reply #11 on: April 26, 2014, 10:06:53 PM »
I usually get this happen to me during winter... I just put it down to the engine and spark plug not being up to temp and fuel condensation. I just ride it out making subtle throttle grabs, as big ones make it worse.

Never thought too much bout it really... I remember on my old sisters GSX250, you really had to warm that sucker up before moving off, god forbid it stopped, it'll never start again....lol

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